2019 13" Dell XPS 13 7390 [10th,6C,U] + GTX 1080 @ 32Gbps-TB3 (AORUS Gaming Box) + Linux & Win10 1909 [sadxps]  

System specs 

2019 13-inch Dell XPS 13 7390, i7-10710U, 16GB RAM, 2TB Samsung Evo 970 Plus
2x 2560x1440 144hz Dell 27" Gaming Monitors (S2719DGF)
MX Keys, MX Anywhere 2, Creative Pebble Speakers

eGPU hardware

Aorus Gaming Box + GTX 1080 + 1.5M TB3 Cable

Hardware pictures 

Installation steps

Windows
Performed fresh install with 1909 USB, let windows updates download all required drivers while EGPU was plugged in.

Debian
Installed nvidia proprietry drivers
Created egpu.conf file in /etc/X11/xorg.conf.d/disabled/egpu.conf

Added the following to .bashrc

# startx if logging in on tty1
#if [ -z "$DISPLAY" ] && [ $(tty) == /dev/tty1 ]; then
#    startx; logout
#fi

# If not running interactively, don't do anything
case $- in
    *i*) ;;
      *) return;;
esac


# startx if logging in on tty1
if [ -z "$DISPLAY" ] && [ $(tty) == /dev/tty1 ]; then
  # Automatically detect EGPU and change xorg.conf accordingly
  # requires egpu.conf in /etc/X11/xorg.conf.d/disabled/
  DIR=/etc/X11/xorg.conf.d
  FILE=egpu.conf

  TEST=$(lspci | grep -c " VGA ")

  #Check for number of GPU's --
  if ([ $TEST -eq 2 ]); then
    #egpu connected
    if ([ -e $DIR/$FILE ]); then
     break ;
    else
      cp $DIR/disabled/$FILE $DIR/$FILE
    fi
  else
    #no egpu
    if ([ -e $DIR/$FILE ]); then
      rm -f $DIR/$FILE
    fi
  fi
    startx; logout
fi

Benchmarks (External Monitor)

UserBenchmarks: Game 104%, Desk 135%, Work 83%
CPU: Intel Core i7-10710U - 87.7%
GPU: Nvidia GTX 1080 - 99.6%
SSD: Samsung 970 Evo Plus NVMe PCIe M.2 2TB - 341.8%
RAM: Hynix H9CCNNNCLGALAR-NVD 2x8GB - 71%
MBD: Dell XPS 13 7390

Comments 

I recently upgraded from the Dell XPS 13 9360 and so far gaming performance seems better but the system runs much hotter and louder. I did undervolt and add thermal pads to the Dell XPS 13 9360 so I will have to investigate that on this new system and report back.1